Hypodermic syringe



Nov. 10, 1953 D. Q. FURNELL HYPODERMIC SYRINGE Filed May 8, 1952 4 IN VEN TOR. 2w Qfkr/zefl BY Patented Nov. 10, 1953 UNITED STATES PATENT OFFICE HYPODERMIC SYRINGE Dale Q. Furnell, St. Paul, Minn.

Application May 8, 1952, Serial No. 286,714

2 Claims. 1

My invention relates generally to hypodermic syringes and, more particularly, to improvements in hypodermic syringe construction.

In utilizing devices of this character for the purpose of withdrawing a sample of blood from a vein, it is important that visual observation be made to insure proper withdrawal of the blood. For this reason, syringes of the above type are generally fabricated from transparent material such as glass, both the barrel and plunger being made from the same material. This construction has necessitated pre-selection between the barrels and their cooperating plungers to insure a proper working fit therebetween, for the reason that difiiculty is experienced in manufacturing glass barrels and plungers having dimensions of the uniformity demanded for proper operation. Hence, in the event that either the glass barrel or its cooperating glass plunger is broken or otherwise damaged, the entire syringe must be disposed of and replaced. An important object of my invention is, therefore, the provision of a hypodermic syringe as set forth which is machined to the close tolerances necessary for interchangeability, so that, if one of the component parts is lost or damaged, it may readily be replaced without the necessity of purchasing an entire instrument. To this end I provide a syringe barrel and cooperating plunger fabricated from suitable corrosion-resistant material such as stainless steel and the like.

Another object of my invention is the provision of increased drawing power of the syringe as compared to a glass syringe. I accomplish this by manufacturing the syringe from stainless steel, which permits closer tolerances of fit between plunger and barrel than are possible in the use of glass.

A still further object of my invention is the provision of a device of the class described in which the plunger and the barrel are formed from non-corrosive metals and may, therefore, be subjected to sterilization indefinitely without changing the tolerances thereof; whereas, instruments formed of glass are subject to change in tolerance with repeated sterilization.

Another object of my invention is the provision of a device of the class described which is provided with a readily replaceable transparent conduit, formed from glass or plastic, and which is interposed between the barrel and the needle in the needle-mounting member.

Another object of my invention is the provision of a metallic hypodermic syringe having means e y the f ow of fluid thereinto or outwardly therefrom may be observed by the operator.

A further object of my invention is the provision of a syringe as set forth which may be quickly and easily dismantled for cleaning and sterilizing and which may as easily be reassembled for use.

Another object of my invention is the provision of a hypodermic syringe which is relatively inexpensive to manufacture and which is efilcient in operation, rugged in construction and durable in use.

The above and. still further highly important objects and advantages of my invention will become apparent from the following detailed specification, appended claims and attached drawings.

Referrin to the drawings, which illustrate the invention and in which like characters indicate like parts throughout the several views:

Fig. 1 is a view in side elevation of a hypodermic syringe built in accordance with my invention;

Fig. 2 is a view partly in elevation and partly in axial section taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 1; and

i Fig. 4. is an enlarged transverse section taken on the line 4--4 of Fig. 2.

Referring with greater detail to the drawings, the numeral I indicates in its entirety a syringe barrel preferably tubular in form providing an axially extended recess 2. At its upper end, the barrel l is provided with a circumferentially extended radially outwardly projecting flange 3 which is flattened at its opposite sides, as indicated at 4, to prevent the barrel from rolling on a table, tray or the like when the same is deposited thereon. A plunger or the like 5 is mounted for longitudinal sliding movements in the recess 2 and, at its outer end, is provided with a handle-forming flange 6 which is disposed longitudinally outwardly of the upper end of the barrel I when the plunger 5 is bottomed in the recess 2. The barrel l and the plunger 5 are both preferably made from corrosion-resistant metal such as stainless steel and the like, the wall of the recess 2 and the exterior of the plunger 5 being ground or otherwise machined within dimensional tolerances which will insure a proper operating fit of the plunger within the barrel. In fact, the barrel and plunger can be machined to tolerances sufficiently close to permit interchangeability of parts. In other words, in the event that a plunger for a given syringe is damaged or lost, a second plunger of the same nominal size may be purchased and utilized with the original barrel, without the necessity of handfitting or any further finishing necessary to efiect a satisfactory fit between the barrel and the new plunger.

The lower end of the barrel 1 is formed to provide a diametrically reduced portion 1 which is externally threaded to receive the internally threaded upper end portion 8 of a needle mounting member 9. The needle mounting member 9 is provided with an axially extended upwardly opening recess I0, the upper end portion of which is defined by said internal threads and is formed at its bottom to provide a relatively fiat annular seat II. A transparent conduit l2 preferably made from glass tubing is slidably contained in the recess I9, its lower end being seated on the annular seat H, its upper end being engageable with the fiat end 13 of the reduced portion or neck 1 of the plunger I when the needle mounting member is screw-threaded thereon. The conduit I2 defines an axial passage M which is axially aligned with an axial passage l extending through the reduced portion '1 and communicating with the recess or chamber 2 in the barrel. At its lower end, the passage 14 in the conduit 12 is aligned with an axial passage [6 extending downwardly from the recess l0 through a tapered shank I! integrally formed with the mounting member 9. A plurality of circumferentially spaced sight apertures 18 extend transversely through the mounting member 9 intermediate its ends to expose portions of the conduit l2 to the view of the operator, for a purpose which will hereinafter become apparent.

The lower end portion of the needle mounting member 9 is formed to provide an internally threaded skirt l9 concentric with the tapered shank l1 cooperating therewith to receive and support a head 20, to the lower end of which is rigidly secured a hollow hypodermic needle 2|. The needle 2| and head 20 thereof are of conventional design, the head having an upwardly opening recess 22, the side wall of which is tapered to correspond to the taper of the shank H. The head 20 at its upper end is provided with external threaded portions 23 which have screw-threaded engagement with the internal threads of the skirt I9 to securely lock the needle against accidental displacement.

When the recess or chamber 2 contains a supply of fluid to be administered, the amount of the injection can be quickly and easily determined by the indicia on the plunger 5 outwardly of the upper end of the barrel I, and it is not usually necessary to determine whether or not the recess or chamber 2 and the passages l4, l5 and 16 contain fluid by means other than inspecting the point of the needle 2 I.

On the other hand, when liquid is drawn from a bottle or ampule, or from a vein, into the chamber 2 via the needle 21, the operator can tell at a glance through the sight apertures 18 if fluid is being drawn into the chamber 2 when the plunger 5 is moved in a direction longitudinally outwardly with respect to the barrel I.

Disassembly of my novel syringe for cleaning and sterilizing is achieved by merely unscrewing the needle from the member 9, the mounting member 9 from the barrel 1, and slidably removing the conduit 12 from the member 9 and the plunger 5 from the barrel I. Obviously, reassembly of the several parts may be effected with equal facility.

My invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and while I have shown and described a preferred embodiment of my novel hypodermic syringe, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention as defined in the claims.

What I claim is:

1. A hypodermic syringe comprising a metallic cylindrical barrel, a metallic plunger closely fitting said barrel and longitudinally slidable therein, said plunger having a handle portion at one end which projects longitudinally outwardly of one end of the barrel, a hollow metallic needle mounting member detachably secured to the other end of the barrel, said member having an axially extended recess in one end and a passage extending from the bottom of the recess to the opposite end of the member and communicating with the interior of a hollow needle mounted on said opposite end, and a transparent conduit in said recess, one end thereof being seated at the bottom of the recess and the other end thereof being adapted to be seated against the last mentioned end of the barrel in communication with the interior thereof when said mounting member is secured thereto, said needle mounting member having a transverse sight aperture therein whereby fluid in said transparent conduit may be observed by the operator.

2. The structure defined in claim 1 in which said sight aperture extends through diametrically opposite portions of said member.

DALE Q. FURNELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,100,181 Hart June 16, 1914 FOREIGN PATENTS Number Country Date 415,132 Italy Sept. 28, 1946 

